Understanding Substantial Similarity: How Does it Impact Your Copyright Infringement Claim?

by Sydney D. Finlay and Clayton Zipperian

One of the most important bars that a potential copyright infringement lawsuit must overcome to be considered by a court is the test of substantial similarity.  Substantial similarity is the level of resemblance at which an alleged infringement becomes valid, and the appropriated work in question is deemed to be derivative of a plaintiff’s copyright-protected material.  It is often a requirement of substantial similarity that two works share unique and protectable elements. For example, a plaintiff cannot claim infringement on the basis that both their novel and a more recent publication are set in New York City.  If both works are set in New York City in a specific year, however, and center their focus on a creatively unique event (i.e. an attack on the city by a horde of radioactive ants and beetles), there may be a pursuable claim of substantial similarity. 

What makes substantial similarity special? 

Substantial similarity is a uniquely critical yet subjective point of contention within a given copyright lawsuit.  Because substantial similarity doesn’t entail the application of an objective set of criteria, different courts can employ different standards of judgment to determine whether substantial similarity exists between two given works.  Given that copyright protection is automatically conveyed to any original works upon creation, it’s nearly impossible to establish a universal standard by which their uniqueness can be appropriately evaluated.  There are, however, steps that you can take to ensure that your work is protected and doesn’t infringe upon the originality of others. 

How can I determine substantial similarity? 

The most frequently used method to determine whether two works are substantially similar is one known as the “extrinsic/intrinsic test.” The Ninth Circuit Court of Appeals defines the extrinsic test as “an objective comparison of specific expressive elements” and the intrinsic test as “a subjective comparison that focuses on whether the …audience would find the works substantially similar.”  These tests are conducted sequentially, with the extrinsic test necessarily preceded by its intrinsic counterpart.   

How does the extrinsic test work? 

The extrinsic test consists of a thorough dissection of the works at hand in order to draw direct comparisons between certain elements, motifs, and other forms of expression that might constitute a creative overlap in violation of copyright protection.  The Ninth Circuit has found that except for specific cases where “the idea underlying the copyrighted work can be expressed in only one way”, the extrinsic test does not require exact copying to have taken place in order for a court to determine that two works exhibit substantial similarity.  Critically, a court’s decision to deem two works as satisfying the extrinsic test does not entail substantial similarity, but rather a choice to move forward with the matter at hand by way of the intrinsic test.  A court must decide that the extrinsic test is satisfied for the works in question to be further evaluated by the intrinsic test. 

How does the intrinsic test work? 

The intrinsic test is conducted by a jury that operates as a microcosm of the works’ potential audience.  Prior to carrying out the intrinsic test, the jury in question is provided with background information regarding the elements of a plaintiff’s work that are not protected by copyright law, the surrounding and relevant legal standards, and are told to consider the work “as a whole”.  Unlike many other forms of trial judgment, expert testimony is not permitted prior to or during the intrinsic test.  Any disruption of the blindness of the “average” viewing audience is frowned upon.  Thus, the verdict delivered by a jury is taken to be the opinion of the average audience.  Copyright infringement cases are unique for this very reason – while many other forms of jury verdicts seek to be as informed as possible, and actively seek out expert testimony and analysis to bring the jury to a more informed position, the entire crux of the intrinsic test is that the only appropriately informed opinion is indeed an uninformed one. 

What does this mean for your copyright-protected IP? 

While the intrinsic test may be an inherently subjective one, that does not mean that preparation and solid argument are not key to winning a potential infringement lawsuit.  Not only does a case have to make it past the extrinsic test to even be considered, but the jury’s opinion also can be heavily impacted by what the court deems as protectable material to begin with.  For these and many other reasons, enlisting expert counsel is imperative to protecting your intellectual property in the arena of copyright law.  If you are considering pursuing legal action against potential infringement, or are seeking to protect your own intellectual property, contact the attorneys at Miller Shah LLP for a consultation today.